Anatomical surfaces can be extracted from a volume of medical imagery through segmentation, which is the process of labeling image voxels according to the tissue type represented. Many anatomical surfaces can be described as two dimensional (2-D) manifolds embedded in three dimensional (3-D) space. The simplest example of this is a plane oriented in three dimensional (3-D) space. However, unlike this simple example, manifolds can have non-linear characteristics.
In some imaging applications, it would be desirable for a user to be able to interact with the manifold by drawing upon it in some way. The drawing could be used to perform quantitative measurements such as to measure distances, surface areas, or volumes. An additional use is in the analysis of local properties such as thickness and curvature of the 3-D surface at specific locations. Another use is in the acquisition of targeting information that will serve as graphical cues in image guided surgery. However, in the current arrangements found in the art a user who needs to draw on the manifold surface needs to somehow maneuver a 3-D drawing device while viewing a 3-D rendering for feedback. This is cumbersome since a user would need to perform simultaneous tasks such as navigating a 3-D view and drawing, especially when portions of the surface are occluded from the user's view. While there are significant advantages in allowing a user to interact with the manifold there are problems that need to be resolved because the surfaces, although intrinsically 2-D in nature, are actually 3-D.
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for a system and method for interacting with an anatomical surface. Additionally, there is a need in the art to perform flattening for the purpose of providing the user with a surface on which to interactively draw easily and accurately. The surface could be flattened onto a plane, then a user could draw on it more easily and more accurately. Furthermore, the user could interact with a virtual surface, or an augmented surface. That is, instead of rendering just the flattened surface as the 2-D image on which to draw, the rendering could be a map of surface properties, such as thickness or curvature.